Method of making urea phosphate



' Patented Dec. 26, 1922.

om'rao STATES- PATENT crime.

runes oLA'RKsoN Ann JOSEPH u ns-Am, or wnsnme'ron, DISTRICT or oonnmnm.

-METHOD OF MAKING unmi PHOSPHATE.

No Drawing.

The main object of the invention is the provision of- .a simple, cheap and efficient; method or proc'es'sflfor making urea phosphate which will give comparatively-high yields.

The invention relates toce'rtain new and useful improvements in the process of mak- 111 urea hosphate. from urea and hosa: P P

phoric' acid. Urea hosphate consists of urea and phosphoric acid in equi-molecular proportions and is formed. substantially in accordance with the following chemical equation: I

The product contains 21.5% ammonia and 4A9 phosphoruspentoxide, a. ratio of ammonia to phosphorus p'entoxide of 1 to 2.1, which is a very highl desirable ratio for fertilizing'materials. it is known that urea. phosphate is readily absorbed and assimilated by plants and that it. produces no deleterious effect upon them. Urea phosphatecan be used alon or mixed with other prepared fertilizer ma rials and it has the furtheradvantages of being readily soluble in Water and relatively non-hygroscopic, absorbing water to the extent-of only 0.54% of its original ,weight iii three We'eks while subjected toan atmosphere of 80% relative humidity at 30 C. Although it is obvious that urea phosphate is excellently suited as a fertilizer material, it can also be used for many other purposes to which such a com- .the vessel with 2.

Application filed June 28, 1921. serial-no. 481,085.

ing amount of urea, (such amount of urea that the ratio of urea to phosphoric acid will be equi-molecular) heating'until all the urea. has "one intosolution, filtering, and cooling to e -ect crystallization.

In our study of the formation of urea phosphate the procedure as outlined'in the above mentioned German patent was first carried out. We added to 100 grams of 50% solution by weight of phosphoric acid (HJOJ containing 0.51 mols. of phos-' phoric acid, 30.6 grams of urea (0.51 molecule heated to 80 C. and cooled to 2 C. No solid phase appeared at this temperature even after considerable scratching of p glass rod to induce crystallization.

lVhile experiments carried out as above set forth gave no yield of ureaphosphate,

it was found that by seeding, that is, adding a few crystals of urea phosphate to the solution to induce crystallization, some urea phosphate would crystallize out, givinga German patent.

- Our next experiment cons'isted in adding 114 grams of ureato 159 grams of a solution of 63% phosphoric acid (approximatelyt2 mols, of. urea to 1 mol. of phosphoric acid) and then heating to C: to effect complete solution. On cooling this solution to'about 20 C'., 80 grams of solid were separated which was shown by the following analysis to be urea phosphate.

Composition of urea phosphate.

' Theoretical. Found. Urea nitrogen phosphorus- 17.71% 17.65% Pentoxidenna $4.947!) 43.83%

This last experiment was then repeated with substantially the same results. It is therefore seen that it is'the acid concentration rather than the urea concentration that effects the separation of urea phosphate.

Experiments were then made using phosphoric' acid concentrations of 55, Z(), 77 .5

cooling the solution of 16 C. The yields decreased with decrease in said concentrations but were above 50% in all these experiments;

These experiments clearly show that an.- acid concentration considerably above 50% is desirable and further that the exact ratio of concentration of acid and urea 1n solutlon 15 not of great importance.

We prefer to'carry out our process in the following manner:

. To a solution of phosphoricacid having a concentration of about 75% is added urea in such an amount that there is present about one mol. of urea to one mol. of phosphori acid. If desired the urea may be added in the form of its solution. In any case the concentration conditions should be sub'stan- I I 'i comprising bringing together themother liquor from which solid urea phosphate has tially as described above.

Having obtained a solution by the method outlined above, the crystals of urea phosphate may be separated from the solution in a dry state by any of the well known methods employed for such a purpose. Due to the fact that urea phosphate has a marked tendency to form a super-saturated solution it may in some cases be advisable to induce or hasten crystallization by inoculating with crystals of urea phosphate, it is understood, of course, that the mother liquor obtainedin this process may be used over and over again. lit is desirable, however, to carry out the process in such-a manner thatthe evaporation required shall be a minimum due to the fact that urea in phosphoric acid solution undergoes decomposition, the rate of decomposition increasing rapidly with temperature especiallyabove90 G. However, this decomposition will in general in volve no loss of ammonia, due to the formation of ammonium phosphate.

Although we have-set forth in considerable detail the manner in which we prefer to carry out our process we do not wish to be limited to the exact conditions herein described but desire to include such changes y '1. The process of making urea phosphate,'

comprising bringing together a solution of phosphoric acid of a concentration of at least 55% by weight of the compound H 1 0, and ureain "such proportions that there is "present substantially one mol. of

tir'ea to one moi. of phosphoric acid.

2. The process of making urea phosphate, comprising bringing together a solution of phosphoric acid of a concentration of at least 55%. by weight of the compound H 1 0 and a solution of area, in such proportions that thereis' present about one mol.

of phosphoric acid to one mol. ofureai' 3. The process of making urea phosphate, comprising bringing together phosphoric acid ina fluid-state and a solution of urea will be at least 55% by weight of the com -pound ILP'O and there. will be present about one mol. of phosphoric acid to one mol. of urea. I f

4. The process of making urea phosphate,

been separated with urea and phosphoric acid in such-amounts and proportions that there is a concentration. of at least 55% by weight of phosphoricfacid and there is present about one mol. of urea to one moi. of phosphoric acid. I

5. The process of making urea phosphate, comprising bringing together the mother liquor from which solid urea phosphate has been separated with urea in such amounts and proportions that there is a concentration of at least 55% by weight of phosphoric acid and there is present about one mol. of urea to one mol. ofphosphoric acid.

-6. The process of making urea phosphate comprising bringing together the mother liquor from which solid urea phosphate has been separated with phosphoric acid insuch amounts and proportions that there is a concentration of at least 555-}; by weight of phosphoric acid and there is present about onedmol. of urea to one mol. of phosphoric aci FULLER GLARKSUN. JOSEPH M. BRAHAM. 

